<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8">
    <title>Document</title>
  </head>
  <body>
    <script>
      var arr = [80, 75, 69, 95, 92, 88, 76];
      var sum = 0;
      for (var i = 0; i < 7; i++) {
        sum += arr[i];				      // 累加求和
      }
      var avg = sum / 7;				    // 计算平均分
      console.log(avg.toFixed(2));	// 输出结果：82.14
    </script>
  </body>
</html>